| 摘要 |
A process for improving the fatigue and stress resistance of transformation hardenable metal turbine blades and other workpieces. The metal is preferably selected from the alloy groups Fe-C, Fe-30%Ni, Fe-12%Cr, and titanium-based alloys. The process includes the step of selectively applying a pulsed heat source to a preselected area of the root of the turbine blade or other preselected area of a workpiece. The step of selectively applying a pulsed heat source is carried out in the absence of carbonaceous material, so that absorption of carbon into the steel does not take place to a significant extent. Controlled pulsing prevents melting of the metal. The process includes the step of inducing a localized martensitic reaction at the preselected area to provide a hardened area having compressive stress. According to one embodiment, the pulsed heat treatment is carried out with an inductive heating element. In another embodiment of the present invention, the pulsed heat treatment is carried out by adding a coupling material to the preselected area in order to enhance light absorption, and directing pulses of a carbon dioxide laser beam onto the preselected area.
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